Minor cleaning of `test_cuda.py` (#46617)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/46617
Sort includes, fix deprecated test warning
Test Plan:
```
buck run mode/dev-nosan //caffe2/test:cuda
```
Reviewed By: drdarshan
Differential Revision: D24429247
fbshipit-source-id: 65f53d7c904032e5c8f8ca45d1d2bb437358ffdd
